Mortality Rates Hold Steady for Women With Diabetes

ATLANTA, June 19 -- Mortality rates for men with diabetes -- but not for diabetic women -- have declined in tandem with the general population's drop in cardiovascular mortality.

A review of data from three large population-based cohorts showed no significant declines in either cardiovascular deaths or all-cause mortality among women with diabetes from the periods spanning 1971-1986 to 1988-2000, reported Edward W. Gregg, Ph.D., of the CDC, and colleagues,

"Our examination of U.S. adults with self-reported diabetes suggests that the well-documented reductions in mortality rates in the general U.S. adult population during the last 25 years have included men with diabetes, but their female diabetic peers have been left behind," the authors wrote online in the Annals of Internal Medicine, scheduled for print in the Aug. 7 issue.

Although the study was not designed to examine the reasons for the disparity, it may have to do with gender-based inequities in care, suggested cardiologist Nanette K. Wenger, M.D., of Emory in Atlanta, in an accompanying editorial.

"Are women with coronary heart disease and diabetes less likely to receive appropriate care?" Dr. Wenger asked. "The answer appears to be yes."

Several studies have shown that coronary heart disease is diagnosed at a later stage in women, that women receive fewer preventive measures than men, and that women less often receive guideline-based therapies during hospitalization or after discharge for an acute coronary event, she wrote.

The study by Dr. Gregg and colleagues tried to answer the question the question of whether the reported decline in all-cause mortality and cardiovascular disease mortality rates also applies to Americans with diabetes.

They compared three consecutive cohorts in the National Health and Nutrition Examination Surveys (NHANES I, II, and III), spanning the years 1971-75, 1976-1980, and 1988-1994, with mortality rates determined through 1986, 1992, and 2000, respectively.

The participants ranged in age from 35 to 74, and included adults both with and without self-reported diabetes.

The authors found that the age-adjusted all-cause mortality rate among men with diabetes declined from 42.6 per 1,000 annually in 1971-86, to 24.4 per 1,000 in 1988-2000 (P=0.03), for a rate ratio of 0.61 (95% CI 0.43 to 0.86). The slope of the decline was similar to that seen in non-diabetic men, which went from 19.0 per 1,000 in 1971-86, to 11.6 per 1,000 from 1988-2000 (rate ratio 0.68. 95% CI 0.57 to 0.81).

Similarly, cardiovascular disease mortality trends in diabetic men paralleled those of all-cause mortality, declining from 26.4 annual deaths per 1,000 in 1971-86, to 12.8 annual deaths per 1,000 in 1988-2000 (P=0.06).

When they looked at women with diabetes, however, they found that there was no decline in either all-cause mortality of cardiovascular disease mortality from 1971-1986 to 1988-2000.

The all-cause mortality rate for non-diabetic women went from 10.1 per 1,000 in NHANES I (1971-1986) to 7.7 in NHANES III (1988-2000). Similarly, the cardiovascular mortality rate among non-diabetic women went from 4.7 in the NHANES I cohort to 2.3 in the NHANESS III cohort.

Among diabetic women, all cause mortality rose from 18.4 per 1,000 from 1971-1986 to 25.9 from 1988-2000, and cardiovascular disease-related deaths went remained essentially unchanged, at 10.5 per 1,000 in NHANES I. to 9.4 per 1,000 in NHANES III.

In addition, the difference in the all-cause mortality rate between diabetic and non-diabetic women increased by more than two-fold, from a difference of 8.3 annual deaths per 1,000 in NHANES I, to 18.2 per 1,000 in NHANES III.

The authors wrote that the decrease in death rates of diabetic men may be attributable to better control of cardiovascular disease risk factors and to improvements in interventions.

"These national data reveal three key findings," Dr. Gregg and colleagues wrote. "1) Reductions in mortality occurred among diabetic men but not among diabetic women; 2) disparities in mortality rates between women with and without diabetes have worsened; and 3) the female-over-male advantage in mortality rates among the diabetic population has been eliminated."

They called for further research into gender inequities in care of patients with diabetes, and for improved public health efforts to lower mortality rates among diabetes patients in general, and women with diabetes in particular.

"We lack an evidence-based comprehensive strategy for improving cardiovascular outcomes in diabetic women," Dr. Wenger wrote in her editorial. "Until we do, a prudent clinical approach involves two steps. First, recognize that diabetic women are at excess risk of developing coronary heart disease. Second, take an aggressive, guideline-based approach to coronary heart disease risk factor management."

Dr. Gregg and colleagues noted that their study was limited by the fact that diabetes was assessed by self-report, and that the study had insufficient statistical power to examine the factors explaining mortality trends.